This invention relates to a ski binding.
The connection of skis to skier's feet is currently implemented as a combination of two elements which are complementary to each other, namely ski bindings and ski boots or shoes, the ski bindings being attached to the skis.
During the skiing action, the boot is held secured to the ski by the binding, the boot being in turn effective to prevent the tibia of the skier from moving forward and backward as well as sideways.
Modern ski bindings are designed such that when the relative stresses between ski and boot exceed a certain value, the boot is released from the binding and comes loose from the ski.
The majority of ski bindings comprise a toe piece and a heel piece secured to the ski, respectively located facing the boot toe and boot heel portions; the boot is made rigid with the ski by these two members of the binding which compress its sole portion axially and against the ski upper surface back.
Some ski bindings further include a plate member acting as an intermediate member between the sole, and toe and heel piece, respectively. With this arrangement, a drawback of prior art bindings is obviated: i.e. the contact areas between the boot heel and sole, which for a given binding have a set that varies with the boot type, and for a given boot design with the binding type. The cited plate member acts as a more accurately fitting and suitable sole for that type of toe and heel piece pair. In any case, however, the connection of the boot to the ski is provided by the strong pressure exerted by the sole, or additional plate, on the ski.
Structurally, the ski boot is essentially a rigid tube wherethrough the calf portion of the skier's leg is inserted. The basic function of the boot/tube is to prevent the tibia from moving sideways with respect to the ski, in order to achieve so-called "edging", which involves stresses that the ankle is anatomically unsuited to withstand, since the human foot is built for resting flat onto the ground. (The more rigid is the boot, the higher is the edging attitude).
Concurrently with the above, the boot also prevents the tibia from swinging freely forwards and backwards. Whereas a backward constraint may in some instances contribute to the skier's balance, who thus gets support against a backward tip, the impossibility of leaning the tibia forwards adversely affects the power of absorbing ground irregularities (such as humps and hollows), and forces the skier to an unnaturally set back position with attendant rearward shifting of his center of gravity to an attitude which is inconsistent with a good skiing attitude.
Furthermore, in the event of a fall, such an inability to lean the tibia, particularly when falling on the face, prevents the skier from reacting in a most natural of manners and taking a falling attitude of least hazard.
It is indeed in the most hazardous of falling conditions, i.e. when the ski is at a hollow in the ground, under high bending load (tip and tail portions raised, middle portion of the ski loaded downwards), that the combined pressure of the toe and heel pieces against the sole, and of the latter against the ski, increases enormously, thus hindering the release of the binding.
Finally, as regards the ski boot itself, it is a heavy kind of footwear, quite unsuitable for normal walking or car driving purposes, being destructive of any sensing capacity of the foot. Since the boot is made rigid externally, the required inner padding in combination with the soft flesh tissues surrounding the tibia, adding to the play created between the sole, heel and ski, does not permit a proper control of side inclination, the foot moving within its seat, while the use of ski boots, besides favoring the insurgence of fractures in the longer bones, also invites edema, lesion, and deformation, as well as poor blood circulation to the lower limbs.